共查询到20条相似文献，搜索用时 62 毫秒
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为了减少温室加温能耗,基于植物生理设计了温室地下蓄热系统,测试了系统冬季白昼蓄热与夜间加温时温室内空气温度、湿度和地坪温度和室外气温、土壤温度、相邻未蓄热温室气温和地温。结果表明：在冬季白昼为晴朗、多云时,系统蓄热可分别使地坪温度平均高于未蓄热温室地温4.8℃,4.4℃,具有良好的蓄热效果;阴天时蓄热时间应适当缩短,但由于长期蓄热,其地温仍高于相邻温室2.6℃。在白昼为晴朗、多云、阴天的情况下,夜间系统加温使温室内气温分别高于相邻未蓄热温室3.1℃,2.0℃,1.5℃,与外界分别保持3.95℃,3.21℃,2.35℃的平均温差,在加温期间具有良好的加温效果,至少可以满足温室加温能耗的35.7%。 相似文献
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为研究设计适用于南疆和田地区日光温室冬季夜间增温蓄热设备,设计了日光温室集散热增温系统,改进了系统集散热器,测试了系统冬季夜间增温蓄热效果,分析了系统对日光温室空气温度、相对湿度以及0cm深土壤温度和15cm深土壤温度的影响和系统集放热效率。试验结果表明：系统在典型晴天试验温室较对照温室温度可以增温4.3℃,试验温室较对照温室平均相对湿度降低8.65%;阴天试验温室较对照温室平均温度增温2.4℃,平均相对湿度降低6.8%,且系统综合平均集热效率为52.6%,表明该日光温室增温系统在和田地区富余的光热资源条件下具有显著效果。 相似文献
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日光温室中空板水循环集放热系统设计与集热性能试验 总被引：5，自引：0，他引：5
针对现有日光温室内置式水循环集放热装置存在的集热能力不足的问题,设计了中空板水循环太阳能集放热系统,通过理论分析,结合日光温室热环境模拟预测软件,验证系统可行性。理论计算表明,在室内地面面积400 m2聚苯板墙体日光温室内,系统集热总量可达350 MJ,可供日光温室2~3 d的夜间放热加温。通过现场试验测试系统的集热性能,试验结果表明:系统集热效率最大可达0.93;晴天条件下的系统日蓄热温升约比阴天条件下高1倍;在太阳辐射较弱时,中空板与室内空气的对流换热对集热效率影响显著;在3.3~5.9 m3/h的流量范围内,系统集热量随着水流量增大而增加。中空板系统作为装配式集热系统,建造成本低、简单实用,不占用室内栽培面积,适用于旧温室改造。 相似文献
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对墙体内侧为相变材料的日光温室3层异质结构北墙建立传热模型，采用隐式有限差分方法，建立了相变北墙节点温度离散方程。以墙体内外表面温度为边界条件，通过Matlab编程计算墙体内温度分布，对温室北墙内外表面温度节点进行热平衡分析，计算北墙内外表面与外界环境间换热量，从而分析了日光温室北墙蓄放热特性及墙体与外界换热的特点。通过Matlab拟合工具，建立了晴好天气条件下日光温室北墙体表面与环境间换热量和墙体表面温度、室外空气温度、太阳辐射强度之间的函数关系。研究结果可为日光温室北墙优化设计与评价提供计算参考。 相似文献
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以山西晋中地区日光温室作为研究对象,通过在温室内部布点测量温、湿度的试验和采用CFD进行数值模拟的方法,研究了冬季晴朗天气状况下,采用畦灌方式的日光温室在自然通风条件下内部湿度的分布规律。结果表明,冬季晴朗天气状况下,日光温室在08:00左右湿度达到最高值,14:00左右温度达到最高值;室内温、湿度显著负相关,温度每升高1℃,湿度降低3.31%;温室内部温度实测值与模拟值误差在±3℃以内,湿度实测值与模拟值误差在6.8%以内,整体拟合情况较好,证明了所建立模型的准确性;温室湿度在南北走向、东西走向变化不太明显,垂直方向上分层比较明显。太阳辐射所提供的热量足以维持温室所需,草帘的保温效果显著,无需对温室进行加温,但是温室夜间湿度较高,甚至接近饱和,需要对湿度进行控制。 相似文献
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日光温室太阳能地温加热技术是应用太阳能聚光装置加热介质水,通过介质水的循环加热土壤温度,从而为日光温室作物生长提供适宜的地温。设计研究加装储能罐的日光温室太阳能地温加热系统,并在天津市静海县进行试验应用。效果显示该系统可以有效提高日光温室的地温,冬季地温可以保持在15℃以上,满足果菜生产的地温需求。 相似文献
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Overland water and salt flows in a set of rice paddies 总被引：1，自引：0，他引：1
E. Playn O. Prez-Coveta A. Martínez-Cob J. Herrero P. García-Navarro B. Latorre P. Brufau J. Garcs 《Agricultural Water Management》2008,95(6):645-658
Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m−1) and an infiltration rate of 5.8 mm day−1. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day−1), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day−1 was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration. 相似文献
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瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。 相似文献
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对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。 相似文献
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对《种子法》存在问题的探讨 总被引：1，自引：0，他引：1
李鹏 《农业机械化与电气化》2011,(6):129-130
《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。 相似文献
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About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered. 相似文献
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在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。 相似文献
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Gunter Wriedt Marijn van der Velde Alberto Aloe Fayçal Bouraoui 《Agricultural Water Management》2009,96(5):771-789
We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications. 相似文献
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在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。 相似文献
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车辆ABS控制算法的研究及探讨 总被引：1，自引：0，他引：1
对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。 相似文献